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Bug #31700 explicit destruction of an object not possible
Submitted: 2005-01-26 02:51 UTC Modified: 2010-12-20 11:48 UTC
From: attibln at gmx dot net Assigned:
Status: Not a bug Package: Scripting Engine problem
PHP Version: 5.* OS: *
Private report: No CVE-ID: None
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From: attibln at gmx dot net
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 [2005-01-26 02:51 UTC] attibln at gmx dot net 
Description:
------------
On second call of __destruct() there should be an error message like "object not existing".

(http://www.php.net/manual/de/language.oop5.decon.php)
"PHP 5 introduces a destructor concept <b>similar to that of other object-oriented languages, such as Java</b>. The destructor method will be called as soon as all references to a paticular object are removed or when the object is <b>explicitly destroyed</b>."

My system:
gentoo 2.4.26-gentoo-r9
apache 2.0.51-r1
PHP Version 5.0.3 / Zend Engine v2.0.3

(php) use flags:
-adabas +apache2 -bcmath -berkdb -birdstep +bzlib -calendar -cdb -cpdflib +crypt -ctype +curl +curlwrappers -db2 -dba -dbase -dbm -dbmaker -dbx -debug -dio -empress -empress-bcs -esoob +exif -fam -fdftk -filepro -flatfile -frontbase -ftp +gd -gd-external -gdbm -gmp -hyperwave-api -iconv -imap -informix -ingres -inifile -interbase -iodbc +jpeg -kerberos -ldap -libedit -mcve +memlimit -mhash +mime -ming -mnogosearch -msession -msql -mssql +mysql -mysqli +ncurses -nis +nls -oci8 -odbc -oracle7 -ovrimos +pcntl -pcre -pfpro +png -posix +postgres -qdbm -readline -recode -sapdb -sasl +session -shared -sharedmem +simplexml -snmp +soap +sockets -solid -spell +spl -sqlite +ssl -sybase -sybase-ct -sysvipc +tidy -tiff +tokenizer -truetype -wddx +xml2 -xmlrpc -xpm +xsl +zlib

Reproduce code:
---------------
<?php

class MyDestructableClass {
  function __construct() {
    print "<br />In constructor\n";
    $this->name = "MyDestructableClass";
  }

  function __destruct() {
    print "<br />Destroying " . $this->name . "\n";
  }
}

$obj = new MyDestructableClass();
print( '<br />before destruction' );
$obj->__destruct();
$obj->__destruct();
$obj->__destruct();
print( '<br />before script end' );

?>


Expected result:
----------------
something like:

Fatal error: ... Destruction of not existing object ist not possible! ... in ... on line ...

Actual result:
--------------
Explicit destruction "not possible".
In other words:
Calling __destruct on an object is possible as often it is done.

Patches

Pull Requests

History

AllCommentsChangesGit/SVN commitsRelated reports
 [2005-01-26 09:05 UTC] derick@php.net 
This is expected. To destroy an object use: unset($obj);
 [2005-01-26 20:12 UTC] attibln at gmx dot net 
Well I do not really want to do nitpicking, but why is it called __destruct() if it does _not_destruct_?! Wouldn't be __exit_method() and __start_method() better choosen then?!

As #31701 this behaviour is not real object oriented behaviour. In my opinion the engine should unset an object when __destruct() is called - similar as it's done in other OOL like C++.

To my surprise unset($obj) really executes __destruct(). This should be mentioned in the _documentation_ "Classes & Objects (PHP5) Constructor & Destructor". Additionally advising not to call __destruct() explicitly but using unset() - as it's stated to use keyword new to create an object instead of __construct(). An example:

<?php

class MyDestructableClass {
  function __construct() {
    print "<br />In constructor\n";
    $this->name = "MyDestructableClass";
  }

  function __destruct() {
    print "<br />Destroying " . $this->name . "\n";
  }
}

$obj = new MyDestructableClass();
unset( $obj );

?>
 [2005-01-26 20:23 UTC] attibln at gmx dot net 
Well I'm not quite sure if finishing the script or unset() executes __destruct(), although I rather guess it's finishing the script.

In that case ... well ... all I can say I dislike that behaviour then. Destruct should destruct!
 [2005-01-26 20:48 UTC] helly@php.net 
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

In a garbage collected language like PHP it is impossible to forcefully destruct an instance. If you need that use c++ or other languages that don't have garbage collectors.
 [2010-12-20 11:48 UTC] jani@php.net
-Package: Tidy +Package: Scripting Engine problem
 
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